The LHCb Collaboration has recently observed three narrow pentaquark states—the Pc(4312), Pc(4440), and Pc(4457)—that are located close to the D¯Σc and D¯*Σc thresholds. Among the so-far proposed theoretical interpretations for these pentaquarks, the molecular hypothesis seems to be the preferred one. Nevertheless, in the molecular picture, the spins of the Pc(4440) and Pc(4457) have not been unambiguously determined yet. In this paper, we point out that heavy-antiquark-diquark symmetry induces a model-independent relation between the spin splitting in the masses of the Pc(4440) and Pc(4457)D¯*Σc pentaquarks and the corresponding splitting for the 0+ and 1+ ΞccΣc triply charmed dibaryons. This is particularly relevant owing to a recent lattice-QCD prediction of the 1+ triply charmed dibaryon, which suggests that a calculation of the mass of its 0+ partner might be within reach. This, in turn, would reveal the spins of the Pc(4440) and Pc(4457) pentaquarks, providing a highly nontrivial test of heavy-quark symmetry and the molecular nature of the pentaquarks. Furthermore, the molecular interpretation of the hidden-charm pentaquarks implies the existence of a total of ten triply charmed dibaryons as Ξcc(*)Σc(*) molecules, which, if confirmed in the lattice, will largely expand our understanding of the nonperturbative strong interaction in the heavy-quark sector.< Leer menos